Powered warm air furnace having burner pressure chamber



March 2, 1965 J. 1.. HEIMAN 3,171,400

POWERED WARM AIR FURNACE HAVING BURNER PRESSURE CHAMBER Filed May 24, 1962 3 Sheets-Sheet 1 l mm. 51 0:3 .1 1

nn "9 :44 K

f; j-wq H b FIG. 2- FIG. 1.

INVENTOR.

JORDAN L. HEIMAN March 2, 1965 J. L. HEIMAN 3,171,400

POWERED WARM AIR FURNACE HAVING BURNER PRESSURE CHAMBER 3 Sheets-Sheet 2 Filed May 24, 1962 INVENTOR.

JORDAN L. HEJMAN March 2, 1965 J. 1.. HEIMAN 3,171,400

POWERED WARM AIR FURNACE HAVING BURNER PRESSURE CHAMBER Filed May 24, 1962 3 SheetsSheet I5 HIGH VELOCITY, LON STATIC PRESSURE HIGH PRESSURE IN CHAMBER Low VELOCITY GREATER sun-1c praass'uaz HIGH Pm:ssura|z- IN CHAMBER FIG. I.

d TO DUCTING OF HIGHER RESISTANCE INVENTOR, JORDAN L. HEIMAN United States Patent 3,171,469 POWERED WARM AIR FURNACE HAVlNG BURNER PRESURE QHAMBER Jordan L. Heiman, Olivette, Mo, assignor to international Gil Burner Company, St. Louis, Mo, a corporation of Missouri Filed May 24, W62, Ser. No. $37,332 3 Claims. (Cl. 126-418) The present invention relates to powered warm air furnaces, and it is of special applicability to oil-burning furnaces connected with systems of heating ducts.

Such furnaces must be manufactured in standard sizes, and should be adjusted at the factory for ehicient operation over a range of heating capacities and with varying duct installations. However, extensive variations in restrictions of air flow will occur in the use of a particular installation, as by closing or blocking the how from certain duct registers. Since ducting restrictions cannot be standardized, it has not heretofore been practical to use the same motor powered blower which circulates the air through the heating systems, to pressurize air to the burner. Under conditions of stream flow, any increased restriction to air flow increases the static pressure within the flowing air stream; that is, as its flow velocity is reduced, its static pressure is increased. Conversely, should a restriction be removed or lessened (as by opening a register) the flow velocity will be increased and the static pressure will be reduced. But if burners of combustible fuel, especially oil, are to operate efiiciently, great variations in static pressure of the air supply cannot be tolerated.

Heretofore, if it was desired to supply combustion air under pressure to such a ducted furnace, a separate cornbustion blower would often be used. However, such a blower adds expense and its use is not free from problcms.

The present invention automatically compensates for variations in extent of ducting and the other restrictions to air flow, such as the opening and closing of registers, and makes such a separate combustion blower unnecessary. Air is delivered to the combustion chamber at a fairly constant, relatively high pressure; this increases combustion efficiency. It also minimizes the effects on the flue of winds and other atmospheric conditions; hence, under usual conditions, no barometric flue damper is necessary.

To accomplish these results, the present invention takes advantage of this principle: Although the static pressure decreases as the velocity (and hence the velocity pressure) increases, the total of these pressures does not vary greatly, where the air delivery source is as shown.

This principle is here utilized by diverting a stream flow of air, powered by the furnace blower, from the air flow passageway into a pressure chamber surrounding the apertured wall of the burner. Air scoops divert the air flow in a curved path into a burner pressure chamber, and thus convert its velocity pressure into static pressure. Hence, the burner pressure chamber utilizes both whatever the static pressure was within the air passageway and its increment arising from the conversion of the velocity pressure to static pressure. An automatic pressure-relief valve from the pressure chamber vents any excess pressure, as may occur if duct registers are closed.

A preferred embodiment of the present invention is shown, somewhat schematically, in the accompanying drawings, in which:

FIGURE 1 is a vertical sectional illustration of a powered oil-burning warm air furnace embodying the present invention.

FIGURE 2 is a sectional view taken along the broken line 2-2 of FIGURE 1.

3,l7l,4@li Patented Mar. 2, 1965 FIGURE 3 is a horizontal section taken along line 33-41 of FEGURE 2.

FIGURE 4 is a diagrammatic view showing the furonce of FIGURE 1 installed, connected to short ducts having relatively low resistance to air flow.

FIGURE 5 is a diagrammatic View showing its installation in duct system involving substantially higher resistance to air flow.

FIGURE 6 is a sectional diagram illustrating flows and pressures in the lower part of the furnace when connected to a low-resistance duct system as FIGURE 4.

FIGURE 7 similarly shows flows and pressures if installed in a system involving higher ducting losses such as FIGURE 5.

The embodiment illustrated utilizes under-floor outlet ducts. Installed in an aperture a in flooring b is a central outlet box 0 supplying the plurality of ducts d which extend beneath the flooring b to floor registers e. Fitted to the central outlet box 0 is an outlet connection 11, connected to the sheet metal base plate 12 of the warm air furnace illustrated. Warmed air flows to the ducts d through a large base outlet opening 13, shown centrally located in FIGURE 2, which communicates between the base plate 12 and the outlet connection 11 to the outlet box (7. The outlet system, taken as a whole and including the ducts, will offer substantial resistance to or re striction of the flow of air, greater in the more complex duct system of FIGURE 5 than in the FIGURE 4 simpler system of short ducts. Should any of the registers e be partially or completely closed off, the resistance will be even greater. Such resistance slows the air flow velocity and increases its static pressure within the furnace.

The air is driven by a furnace blower or air circulator 1d, connected to the shaft of an electric motor 16, powered by a source of current not shown, through circuitry which will be understood without illustration. The furnace blower or air circulator wheel 15 is located at the upper or inlet opening it; of an enlarged hollow air casing generally designated 17, whose bottom joins the sheet metal base plate 12 to communicate air flow to the outlet opening 13. Portions of the air casing 17 serve as the side wall 1% and the lower rear wall 19 of the furnace, although these exend forward somewhat beyond the casing 17. The rear upper wall 20 of the air casing 17 is curved rearwardly and down from the inlet 16, in a manner suitable to achieve eificient flow downward from the air circulator wheel 15; there it joins a diagonally-downward sloping rear wall portion 21 which connects to the upper edge of the lower rear wall 19. At the forward part of the air casing 17 beneath its inlet opening 16 is a forward and downward diagonally-sloping portion 232 which joins a vertical forward air casing wall 23, the latter extending downward to the sheet metal base plate 2 as shown in FIGURE 1. Above the upper edges of the sloping walls 21, 22 of the air casing 17, the furnace is equipped with a rectangular cabinet top 24- which, like the sides 18, 19, extend forwardly somewhat beyond the forward air casing wall 23. To them a louvred door 25 is fitted; through its louvres the returning air flows to the air inlet 16. The forward wall 23 of the air casing 17 is functionally the outer wall of the furnace, even though the louvred door 25 screens it ornamentally from view.

Positioned spacedly within the air casing 17 is a heat exchanger generally designated 30, having a hollow sheet metal body 31, of generally rectangular cross-section as shown in FIGURE 3, and having a pyramidal top portion 32. At the rear of the pyramidal top portion 32, a line opening 33 joins a short cylindrical flue connector passage 34 through the air casing sloping rear wall portion 21, to connect to a curved flue passage 34 bounded forwardly by the rear upper air casing wall 20 and at hte rear by a flue Wall 35 of corresponding curvature.

am nes As seen in FIGURE 1, the curved upper. casing wall 20 and fiue wall 35 lead upward to a flue vent connector 36, which extends through the cabinet top 24 and is there connected to a flue 1.

Serving functionally as the bottom of the heat exchanger 31 is an irnperforate burner mounting pan 37, flanged upward to a central circular opening 33, in which is sealedly fitted an oil burner pot 39. The burner pot 39 has conventional upper and middle burner rings 40, 41, a flat imperforate bottom 42 onto which oil may flow for vaporization, a fuel inlet line 43 located immediately above the bottom 42., and a cylindrical burner wall 44 which is perforated by many small air orifices 45 above the level of the fuel inlet line 43. Fuel oil is supplied to the fuel inlet line 43 by a supply source which is conventional and not shown.

In a powered oil-burning warm air furnace such as described, it is important that combution air be supplied under some regulated pressure to the air orifices 45 in the oil burner pot 39, so as to assure eficient combustion. Some prior warm air furnaces have utilized separate combustion blowers for this purpose. The need for such a combustion blower is completely avoided in the present invention, by the features which now will be described.

Below the burner mounting pan 37, the heat exchanger sheet metal body 31 is continued downward to serve as the four side walls 49 of an air pressure chamber generally designated 50, having a horizontal bottom wall 51 spaced above the sheet metal base plate 12. The heat exchanger 30 and air pressure chamber 59 therebeneath together serve as the inner walls which define air flow passageway or, more specifically, a four-sided passageway Whose outer walls are the air casing 17 and base plate 12. The burner mounting pan 37 and oil burner pot 39 serve as top and inner walls of the air pressure chamber 50. The left and right side wall 49 are penetrated with inlets or openings 52 from the air passageway; the inlets 52 are provided with outward-projecting air scoops 53 which divert some of the air from the left and right sides of the passageway in a stream flow into the pressure chamber 50. As shown in FIGURE 2, the air 'scoops 53 extend and are joined to the lower side walls 18 of the air casing 17. The scoops 53 may be relatively narrow; they do not extend across the full width of the furnace, but only such width as is necessary to supply air to the pressure chamber 50 in suificient volume.

To relieve any excess of air pressure within the pressure chamber 50, an excess pressure relief vent valve generally designated 55 is provided in the forward wall 49 of the pressure chamber 50. A circular vent opening 56 in the wall 49 communicates, through a short circular relief duct 57, to the forward wall 23 of the air casing 17. The duct 57 is closed by a horizontally-hinged butterfly valve element 58, weighted for balance by the weight 59. The valve element 58 may be constructed similar to an ordinary barometric flue damper. The weight is set to vent air pressure from the pressure chamber. 50 whenever it reaches a chosen value in excess of the pressure within the room space to be heated.

FIGURE 6 illustrates schematically how, when the furnace is installed to ducting of low resistance, as in FIGURE 4, air will flow through the air passageway at relatively high velocity indicated by relatively long arrows. The low resistance ducting thus results in low static pressure of the air, indicated by widely-spaced dots. When such high-velocity air is diverted in a stream flow into the air pressure chamber, its velocity pressure is converted to additional static pressure, indicated by closely-spaced dots. A relatively high static air pressure in th chamber 50 is thus furnished.

When the same furnace is installed to ducting of relatively high resistance, as the ducting of FIGURE 5, the greater duct resistance will result in greater static pressure in the air passageway, and hence the air will flow from the furnace floor at a lower velocity. The shorter arrows of FIGURE 7 indicate the lower velocity than the long constant; and any excess pressure is vented.

arrows of FIGURE 6; the more closely spaced dots in the air passageway indicate greater static pressure. The

pressure chamber is thus supplied with air having a greater initial static pressure but having lower velocity pressure. Since there is less velocity pressure to convert to static pressure in the pressure chamber, the final total pressure within the chamber 50 under these conditions of FIGURE 7 does not vary greatly from the pressure shown in FIGURE 6.

If the ducting provided exceptionally high resistance, or if some of the registers 6 were closed, the static pressure in the air passageway would be relatively large, and even the small increment of pressure in the chamber 50 due to its low velocity might raise the chamber pressure to a value at which the vent valve would open, relieving any excess.

One result of the present construction is to make it feasible to supply higher air pressures against the perforated cylindrical burner pot wall 45. Except when the vent valve 55 is open, these perforations or air orifices 45 are the only means of escape of air from the pressure chamber 50. Utilizing small orifices 45 and higher air pressure results in greater elficiency of combustion. The differential in such pressure over atmospheric pressure relieves somewhat the effect of winds upon the flue 1; hence no barometric flue damper is necessary under usual conditions. 7

Summing up operational aspects of the present invention: although the particular ducting installation may subject the furnace to an extreme'of static pressure or velocity pressure, the stream flow diversion of the air from the passageway into. the burners pressure chamber supplies it with air whose final static pressure is fairly Hence, combustion is effected under optimum conditions.

Variations in construction and utilization will occur to those skilled in the art. Instead of the simple air scoops 53, more refined means might be employed to convert the velocity pressure of the air in the passageway to static pressure within the pressure chamber. The fuel may be any of the several types commonly burned with a supply of combustion air. The deails of construction of the air casing, heat exchanger, air circulator blower, and other familiar features illustrated may of course be varied without departing from the present invention. Accordingly, the invention should not be construed narrowly, but as fully coextensive with the claims.

I claim:

1. For use as part of a heating system including outlet ducts,

a powered oil-burning Warm air furnace comprising an air casing including an upper inlet opening and a lower outlet connection for connection to such outlet ducts,

a flue-vented heat exchanger spaced within the air casing in the path of the air between the inlet and the outlet connection,

a motor-powered furnace blower within the air casing above and external of the heat exchanger,

an oil-burner pot at the base of the heat exchanger,

the pot having a perforated side Wall,

an air pressure chamber sidewardly adjacent to and communicating its pressure through the perforated side wall of said pot, said air pressure chamber extending beneath the heat exchanger and having an outer wall forming a downward continuation of the heat exchanger wall in the path of the air from the inletto the outlet connection,

the outer surface of the'perforated burner pot comprising part of the inner wall of the pressure chamber,

inlets through said outer wall of the pressure chamber communicating withsuch path of air to the outlet connection, and

air scoops at the inlets and projecting outwardly therefrom into such air path.

2. A powered oil-burning warm air furnace as defined in claim 1,

together further with an excess pressure relief vent valve communicating between the pressure chamber and the outer wall of the furnace.

3. For use as part of a heating system including an outlet duct,

an oil burning warm air furnace, comprising an air casing including an inlet opening and an outlet connection for connecting to such outlet duct,

a flue-vented heat exchanger having a wall spaced within the air casing in the path of the air between said inlet opening and said outlet connection,

a motor-powered furnace blower within the air casing adjacent to the inlet opening and external of the heat exchanger,

an oil burner pot at the base of the heat exchanger,

the pot having a perforated side wall,

an air pressure chamber sidewardly adjacent to and communicating its pressure through the perforated side wall of said pot, said air pressure chamber extending beneath the heat exchanger, said chamber having as one of its walls a perforated wall of said oil burner pot, said chamber further having a wall beneath and forming a continuation of said heat exchanger wall within said air casing and presented along the path of the air flowing from said blower to said outlet connection,

an inlet through said outer wall of the pressure chamber whereby to communicate with such path of air to said outlet connection, and

an air scoop at the inlet and projecting outwardly therefrom into such air path within said air casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,193,735 Mueller Mar. 12, 1940 2,227,773 Warren et a1. Jan. 7, 1941 2,684,667 Glasby July 27, 1954 2,865,364 Cutler Dec. 23, 1958 3,027,889 Krausz Apr. 3, 1962 3,078,837 Mueller Feb. 26, 1963 FOREIGN PATENTS 131,639 Switzerland May 1, 1929 

1. FOR USE AS PART OF A HEATING SYSTEM INCLUDING OUTLET DUCTS, A POWERED OIL-BURNING WARM AIR FURNACE COMPRISING AN AIR CASING INCLUDING AN UPPER INLET OPENING AND A LOWER OUTLET CONNECTION FOR CONNECTION TO SUCH OUTLET DUCTS, A FLUE-VENTED HEAT EXCHANGER SPACED WITHIN THE AIR CASING IN THE PATH OF THE AIR BETWEEN THE INLET AND THE OUTLET CONNECTION, A MOTOR-POWERED FURNACE BLOWER WITHIN THE AIR CASING ABOVE AND EXTERNAL OF THE HEAT EXCHANGE, AN OIL-BURNER POT AT THE BASE OF THE HEAT EXCHANGER, THE POT HAVING A PERFORATED SIDE WALL, AN AIR PRESSURE CHANBER SIDEWARDLY ADJACENT TO AND COMMUNICATING ITS PRESSURE THROUGH THE PREFORATED SIDE WALL OF SAID POT, SAID AIR PRESSURE CHAMBER EXTENDING BENEATH THE HEAT EXCHANGER AND HAVING AN OUTER WALL FORMING A DOWNWARD CONTINUATION OF THE HEAT EXCHANGER WALL IN THE PATH OF THE AIR FROM THE INLET TO THE OUTLET CONNECTION, THE OUTER SURFACE OF THE PERFORATED BURNER POT COMPRISING PART OF THE INNER WALL OF THE PRESSURE CHAMBER, INLETS THROUGH SAID OUTER WALL OF THE PRESSURE CHAMBER COMMUNICATING WITH SUCH PATH OF AIR TO THE OUTLET CONNECTION, AND AIR SCOOPS AT THE INLETS AND PROJECTING OUTWARDLY THEREFROM INTO SUCH AIR PATH. 